Sheet handling apparatus



June 23, 1970 A. G. R. GATES 3,516,353

-SHEET HANDLING APPARATUS Filed June 5, 1967 3 Sheets-Sheet 1 A Horney:

June 23, 1970 A. G. R. GATES 3,516,353

SHEET HANDLING APPARATUS Filed June 5, 1967 3 Sheets-Sheet g Inventor Aftorney:

June 23, 1970 A. G. R. GATES SHEET HANDLING APPARATUS 3 Sheets-Sheet 5Filed June 5, 1967 A ttorney;

United States Patent 3,516,353 SHEET HANDLING APPARATUS Albert GeorgeRonald Gates, London, England, assignor t0 Gestetner Limited, London,England, a British company Filed June 5, 1967, S81. No. 643,499 Claimspriority, application7 317?; Britain, June 15, 1966,

9 Int. Cl. B411 13/06; B41f 13/24 US. Cl. 101-118 6 Claims ABSTRACT OFTHE DISCLOSURE Printing apparatus in the form of a stencil duplicator inwhich the movement of the pressure roller towards and away from theprinting roller is controlled by a pneumatic system comprising a pulsepump communicated with a pneumatic motor by way of a rotary vent valve.The valve is operated by a pivotable sheet sensing lever and thepneumatic motor is engageable with a control lever to connect itoperably with a reciprocating member only when a sheet is present. Thecontrol lever is mounted on a swinging support for the pressure rollerto thus control movement of the pressure roller.

The present invention relates to sheet feeders and more particularly toapparatus for feeding sheets one at a time to associated equipment whereit is important that such equipment or part of it should be inoperativewhen no sheet is being fed thereto. One form of equipment in which thesheet feeder of this invention is particularly useful is a stencilduplicator. In stencil duplicators, the stencil is carried around aprinting cylinder, and sheets of paper are passed one at a time betweenthe stencil on the printing cylinder and a pressure roller which pressesthe paper against the stencil. It is necessary for the pressure rollerto move towards and away from the printing cylinder as each sheet ofpaper is being fed through the duplicator and also for the pressureroller to be prevented from moving towards the printing cylinder when nosheet is being fed through the duplicator. If such movement were notprevented, the pressure roller would contact the stencil and be inkedthereby and then cause soiling of the backs of the sheets subsequentlypassed through the duplicator.

Conventional stencil duplicators have been provided with a paperdetecting device which, by means of a mechanical linkage to the pressureroller movement mechanism, ensures that the movement of the pressureroller is only effected when a sheet is being fed. In our British Pat.No. 973,108 we have described an improved paper detecting and pressureroller control device in which control of the pressure roller iseffected by pneumatic means under the control of means which senses whenpaper is not being fed through the machine. In the constructiondescribed in our said patent, the sensing device comprises a detectorpiston and cylinder arrangement which is positioned above the feed pathof sheets to the printing cylinder and to which, while the duplicator isin operation, alternate pressure and suction pulses are supplied from amaster piston and cylinder arrangement operated in synchronism with theoperation of the duplicator to cause the detector piston to movedownwardly and then upwardly again, once for each cycle of operation"ice of the duplicator. The detector piston is positioned so that, inmoving to its lowermost position, it crosses the feedpath of sheets fedto the printing cylinder. When no sheet of paper is being fed to theprinting cylinder at the time the detector piston moves downwardly, thispiston moves to its lower-most position and in such position permits apressure pulse of air from the master cylinder to be fed to pressureroller control means. This pressure pulse acts to effect disconnectionof the mechanism which normally causes the pressure roller to engage theprinting cylinder of the duplicator at the appropriate time during eachprinting cycle. When, however, paper is being fed to the printingcylinder at the time the detector piston moves downwardly, such pistonis intercepted by the paper and prevented from reaching its lowermostposition. As a consequence, no pressure pulse of air can be sent to thepressure roller control means and the pressure roller operates normally.

It is an object of this invention to provide in a sheet feedingapparatus a paper detecting device which may be used to providepneumatic operation of a mechanism, such as a pressure roller controlmechanism as in the case of the construction of our said prior patent,but is improved as compared with such construction.

Although in the above we have referred particularly to the use of thepaper detecting device in the sheet feeder of a stencil duplicator forproviding control of the pressure roller of such duplicator, it Will beappreciated that this is an illustration only of the use of such device.It may equally well be used in a sheet feeder associated with any otherapparatus for controlling operation of the latter or of part thereof;for example, it could be used in the sheet feeder associated with arotary offset duplicating machine for controlling the printing andblanket cylinders thereof.

According to this invention, there is provided, for use in sheethandling equipment, a paper detecting and equipment control devicecomprising pneumatically operable means adapted to control the actuationof the said equipment or of part thereof, means for producing pressurepulses at a pressure different from atmospheric for operating the saidpneumatically operable means, a guide for guiding a sheet to sheetequipment and a valve controlling the application of said pulses to thepneumatically operable means, such valve having an actuating memberbiased to a position in which it prevents the application of said pulsesto the pneumatically operable means, but arranged so as to be engaged bya sheet of paper as it passes over such guide, so that it is moved bysuch paper sheets to actuate the valve so that said pressure pulses areapplied to the pneumatically operable means.

In the construction according to this invention, the equipment or partthereof controlled by the pneumatically operable means can only beactuated upon receipt of a positive signal that a sheet of paper ispassing to the equipment. Thus, since the equipment or relevant partthereof is not normally actuated and is only caused to operated whenpaper passes to the equipment, any failure of the device will not leadto the equipment being fully operated while no paper is being fedthereto.

Thus, in the case where the device according to this invention isapplied to the sheet feeder of a conventional stencil duplicator withthe pneumatically operable means controlling the actuation of thepressure roller of the duplicator, the pressure roller can only beactuated when a positive signal has been received that a sheet of paperis passing to the printing cylinder. Since the pressure roller is notnormally actuated and is only caused to operate when paper passes to theprinting cylinder, any failure of the device will result only in sheetswhich are fed through the duplicator passing through without beingpressed against the printing cylinder and will not lead to the pressureroller being engaged with the stencil on the printing cylinder of theduplicator. In the construction described in our British Pat. No.973,108, since the pressure roller is normally operated at each cycle ofthe machine and the control device acts to prevent operation of thepressure roller when no sheet is being fed, failure of such constructionwould be accompanied by engagement of the pressure roller against thestencil on the printing cylinder when no sheet is being fed.

Preferably, according to a further feature of the in vention, the valveis of the rotary type in which pivoting of the actuating member operatesthe valve, the mem ber projecting into the feed path of sheets to theassociated equipment so that a sheet being fed thereto will swing themember aside and thereby actuate the valve.

Although the valve could be arranged directly in a conduit from themeans for producing pressure pulses to the pneumatically operable meansso as to control the opening and closing of such conduit,advantageously, according to a further feature of the invention, thevalve is in a branch passage from such a direct connection and the valveoperates either to close such branch passage so that the pressure pulsesare applied to the pneumatically operable means or to open such branchpassage to the atmosphere so that the pneumatically operable means isnot operated.

Conveniently, the pressure pulses are produced by a master piston andcylinder arrangement actuated in synchronism with the operation of theequipment, e.g. in the case of a stencil duplicator from a cam providedon the main drive shaft of the duplicator.

According to a further feature of the invention, the pneumaticallyoperable means preferably comprises a piston and cylinder arrangement towhich the pressure pulses are applied when a sheet is fed to theequipment, such piston and cylinder arrangement being adapted to effectthe desired operation of the equipment or part thereof. Where the deviceis applied to the sheet feeder of a stencil duplicator, the piston andcylinder arrangement is advantageously adapted to pivot a control leverinto the path of a member moving in synchronism with the operation ofthe duplicator, so that such control lever is moved by such member toeffect movement of the 7 pressure roller of the duplicator.

Although, as indicated above, the pneumatically operable means may besuch as to be operated by suction, we prefer to use air under a positivepressure.

In order that this invention may more readily be understood, oneembodiment of a paper detecting device according to the inventionapplied to the sheet feeder of a stencil duplicator will now bedescribed, merely by way of example, with reference to the accompanyingdrawing, in which:

FIG. 1 is a schematic illustration of a duplicator including the devicein the condition when no sheet is being fed through the duplicator;

FIG. 2 shows a cross-section on the line IIII of FIG. 1 to show theposition of the valve;

FIGS. 3 and 4 are views corresponding to FIGS. 1 and 2, but illustratingthe condition when a sheet is passing through the duplicator; and

FIG. 5 illustrates how the operation of the slave piston and cylinderarrangement causes operation of the pressure roller.

The embodiment of device illustrated in the drawing is for the sheetfeeding mechanism of a conventional stencil duplicator of the twincylinder type, i.e. the type which comprises two cylinders mounted onparallel axes spaced one above the other, an ink screen over which thestencil is adapted to be placed passing around these two cylinders. Thesheet feeding mechanism is provided for passing copy sheets of paperbetween the lower or printing cylinder, of the two cylinders and apressure roller mounted below such printing cylinder. However, asindicated above, the device can equally be applied to any form of sheethandling apparatus.

The synchronising of the various ancillary mechanisms of the duplicator,such as the sheet feeding mechanism, with the rotation of the cylindersis effected by these mechanisms being driven from a cam or cams on themain driving shaft 32 of the duplicator. In the duplicator of thisinvention, such shaft 32 has two additional cams, namely an operatingcam 6 for a master air piston and cylinder arrangement and a pressureroller drive cam 14.

The follower for the cam 6 is a roller 15 carried by a pivoted lever 16,such lever engaging a boss 33 on a master piston 4 which is slidable ina master cylinder 5. The piston 4 is reciprocable within the cylinder 5,being forced downwardly into the cylinder by the cam and follower andupwardly again by a helical return spring 17. At a position near the topof the wall of the cylinder 5, the latter is provided with an aperture18 which, in the upper position of the piston 4 registers with anaperture 19 in the wall of the piston. The lower part of the interior ofthe cylinder 5 communicates with a side chamber 20 provided with outlets21 and 22. During operation of the duplicator at each cycle of themachine, the piston 4 is depressed within its cylinder, tending to buildup pressure in the side chamber 20, and is then returned by the spring17 to the position shown in FIG. 1, at which time the interior of thecylinder is vented to atmosphere through the then registering apertures19 and 18.

The outlet 21 of the side chamber 20 is connected by a gas-tight conduit23 to the interior of a hollow valve body 24 which is generally ofcylindrical form. Rotatably mounted on the valve body 24 is a sleeve 25carrying a thin metal finger 1 forming the sensing member which senseswhen a sheet is being fed through the duplicator. The shape and positionof the finger 1 is such that it normally rests in the position shown inFIG. 1 under gravity against the paper fence 2. In this position, anaperture 3 in the finger and sleeve 25 registers with a cross bore 34 inthe valve body 24 and vents the outlet 21 of the side chamber 20 to theatmosphere. Pivoting of the finger 1 upwardly from the positions shownin FIGS. 1 and 2 by a sheet of paper passing through the duplicator willcause the aperture 3 to move out of register with the cross bore of thebody 24 and the outlet 21 thereby to be closed.

The outlet 22 of the side chamber 20 of the master cylinder 5 leads viaa conduit 26 to a slave piston and cylinder arrangement 7, the piston ofwhich engages against a roller 26 mounted on a. control lever 8 which ispivoted on a pin 9 carried by a pressure roller lifting lever 10 (seeFIG. 5). In this condition, the control lever 8 rests against a stop 11.The pressure roller lifting lever 10 is pivotally mounted on a pivot 27on which is also pivoted a two-armed lever 13 having at the end of onearm a follower 28 engaging the cam 14 and at the end of the other arm apeg 12 projecting through a slot 29 in the pressure roller lifting lever10.

In operation of the machine, the cam 14 moves the two-armed lever 13 sothat the peg 12 reciprocates along an arcuate path centered on pivot 27.With the control lever 8 in the position shown in FIGS. 1 and 2, the peg12 moves from the position shown in full lines in FIG. 1 to the positionshown in dotted lines in the same figure. It will be seen that thismovement of the peg 12 is between two limbs 30 and 31 of the lever 8 anddoes not affect the angular movement of such lever. When, however, thepiston of the slave piston and cylinder arrangement 7 moves to theposition shown in FIG. 3 and, by

its engagement with the roller 26, pivots the lever 8 about pin 9 fromthe position shown in FIG. 1 to that shown in FIG. 3, the limb 30engages the stop 11 and the limb 31 moves into a position obstructingthe arcuate path of the peg. 12. Reciprocation of the peg 12 then willmove the lever 8 between the full and dotted line positions shown inFIG. 3. Such movement of the lever 8 would be transmitted to thepressure roller lifting lever by virtue of the connection between thelevers provided by the pivot 9.

The operation of the above-described device is as follows:

The normal condition of the device is that shown in FIGS. 1 and 2 andthe device retains this condition unless a sheet of paper engages thefinger 1. With the device in this condition, the side chamber is ventedto the atmosphere through conduit 23 and aperture 3 in the rotary valve.At each cycle of the duplicator the cam 6 causes the depression of themaster piston 4 in its cylinder 5 but, because the chamber 20 is ventedto the atmosphere, no pressure build-up occurs in the master cylinder 5and the slave piston and cylinder arrangement 7 is unaffected. The lever8 remains in the FIG. 1 position; the peg 12 which reciprocates once foreach cycle of the duplicator engages between limbs and 31 and does notalfect the lever 8 and the pressure roller lifting lever 10 is alsounaffected.

When, however, a sheet of paper 35 passes through the duplicator, asshown in FIGS. 3 and 4, this sheet 35 lifts the sensing finger 1 andcloses the rotary valve by moving aperture 3 out of register with crossbore 34. The chamber 20 is then no longer vented to the atmosphere andthe depression of the master piston 4 in its cylinder 5 causes abuild-up of pressure therein which is transmitted to the slave pistonand cylinder arrangement 7 and moves the lever 8 into the position shownin full lines in FIG. 3. The pin 12 in its reciprocation engages thelever 8 and moves this laterally to the dotted line position shown inFIG. 3, movement of the lever 8 thereby moving the pressure rollerlifting lever 10 which effects lifting of the pressure roller 36 towardsthe printing cylinder 38 so as to press the sheet of paper 35 againstthe stencil passing round the printing cylinder.

It will be appreciated that, if the above-described device fails tooperate, the pressure roller 36 will not be raised and there will be noquestion of such roller coming into contact with an inky stencil.Further, the operation of the device cannot be obviated by hand turningof the machine very slowly as is sometimes possible with theconstruction of our previously mentioned British patent specification.Additionally, the rotary valve 25, the sensing finger 1, the piston ofthe slave piston and cylinder arrangement 7 and the control lever 8 arestationary when the machine is idling and thus unnecessary wear of suchparts is avoided, and the device is quiet in operation since it does nothave a detector piston constantly reciprocating into the path of thesheets fed through the duplicator. The device according to thisinvention allows the machine to be operated by hand feeding if desired.

It is conventional for the stencils which are used with stencilduplicators to be provided with a backing sheet of stiff paper. When thestencil is initially laid on the ink screen, the operator rotates thestencil and attached backing sheet at least once so that the pressureroller may lift and press the backing sheet onto the stencil so that thesencil is properly inked, the backing sheet being torn off thereafter.In conventional duplicating apparatus, a button is provided to overridethe action of the mechanical sheet detector so that the pressure rolleris caused to rise even though no paper is passing through theduplicator.

In the sheet detecting and pressure roller control device of thisinvention, provision may also be made for enabling the pressure rollerto rise when desired, e.g. when wishing to press a backing sheet againsta stencil, even though no paper is passing through the duplicator.

When the backing sheet button (not shown) is depressed it engages theupper surface of the limb 31 of lever 8, and pivots the lever to theposition shown in FIG. 3. When in this position the pressure roller israised even when no paper is fed, and the backing sheet is pressedagainst the stencil.

I claim:

1. Sheet printing apparatus comprising:

(a) a printing roller;

(b) a pressure roller disposed parallel to said printing roller;

(c) pivotable operating lever means carrying said pressure roller formovement towards and away from said printing roller;

(d) a reciprocating member driven in synchronism with the operation ofsaid sheet printing apparatus for movement along a path;

(e) a control lever pivotally mounted on said operating lever means formovement between a first normal position wherein it lies clear of saidpath and a second operating position wherein it lies on said path foroperable engagement by said reciprocating member;

(f) asheet guide;

(g) means driven by said sheet printing apparatus for creating apressure pulse at a pressure different from atmospheric;

(h) pneumatic motor means positioned for operable engagement with saidcontrol lever to move said control lever from said first to said secondpositions;

(j) conduit means joining said pressure pulse creating means to saidpneumatic motor means;

(k) a sensing lever biased towards a first angular position andpivotable to a second angular position by contact with a passing sheetalong said guide; and

(l) a rotary vent valve operably connected to said sensing lever andcommunicating with said conduit means for rendering said pressure pulsecreating means operative on said pneumatic motor means only when saidsensing lever is in its second angular position, and for venting saidconduit means when said sensing lever returns to its first angularposition.

2. Sheet printing apparatus according to claim 1, and including a maindrive shaft, a first cam on said main drive shaft for operating saidpulse creating means, and a second cam on said main drive shaft fordriving said reciprocating member.

3. Sheet printing apparatus as claimed in claim 1, wherein said conduitmeans comprises a first conduit extending between said pneumatic motorand said pulse creating means, and a second conduit forming a branchpassage from said first conduit, said rotary vent valve befng positionedin said second conduit and operating either to close said branch passageor to open said branch passage to the atmosphere.

4' Sheet printing apparatus as claimed in claim 1, wherein said pressurepulse creating means comprises a master cylinder and a master pistonoperably connected to said sheet printing apparatus for drivenreciprocation within said master cylinder.

5. Sheet printing apparatus according to claim 1, wherein said pulse isat a pressure above atmospheric pressure.

6. Sheet printing apparatus as claimed in claim 1, wherein saidpneumatic motor means comprises a slave piston and a slave cylinder towhich the pulse is applied only when said sensing lever is in its secondangular position, said piston being slidable within said slave cylinderand being in operable engagement with said control lever to effectmovement of said control lever between said first and second positions.

References Cited UNITED STATES PATENTS 8 Brigham 101-233 Sandberg 118-2Stuchbery 101-247 XR Gates 101-118 ROBERT E. PULFREY, Primary ExaminerC. D. CROWDER, Assistant Examiner US. Cl.

Sanders et a1. 101-35 10 101 233 247; 271 5

